Strap structure



Mayzq,1945;"v I H. 'L.IZIMMERMAN 2,377,061

. 5 TRAP STRUCTURE Filed April 19. 1943 ATTORNEYS.

Patented May 29, 1945 I RICE STRAP STRUCTURE Herbert Leslie Zimmerman,Shorewood, Wis., as-

signor to The Fulton Company, West Allis, Wis., a corporation ofWisconsin Application April 19, 1943, Serial No. 483,604

6 Claims. (Cl. 248-74) The present invention relates in general toimprovements in the art of metal working, andrelates more specificallyto an improved strap structure and an improved mode of constructing thesame. i

. Generally defined, an object of my invention is to provide an improvedsheet metal strap assembly.

In the manufacture of airplanes as well as other industries, whereinvarious parts are assembled and held in place by means of semi-circularstraps formed of light but strong sheet-metal such as aluminum or thelike, it was heretofore customary to form these straps of curvedsheetmetal bands having attaching or clampingbosses .welded to theopposite extreme-ends thereof. This prior method of constructing suchstraps was not only costly and tedious, but also resulted in theproduction of strap assemblies which were not of uniform and neatappearance, and which were frequently weakened by the weldingoperations.

'In many instances this weakening was not detected until after thestraps were applied to the final assemblages, when they would breakeither while being clamped in position or after the assemblages werecompleted and placed in service. In the case of airplanes, this ruptureof the straps may obviously result in serious accidents, so that theprevious welding method of manufacturing these strap and boss assemblieshas been extremely objectionable.

It is therefore a more specific objectof the present invention toprovide an improved mode of manufacturing clamping strap structureshaving attaching bosses at the ends thereof and which may be formed oflight and strong sheet-metal such as aluminum, with the aid of punchesand dies and without resorting to welding or other heating operations.

Another specific object of this invention is to provide an improvedstrap structure which is simple, strong and durable in construction, andwhich may be readily produced by quantity production methods whereby allstraps are uniform and accurate in structure.

These and other specific objects and advantages of the presentinventionwill be apparent from the following detailed description.

Aclear conception of'the several features involved in my presentimproved mode of strap production, and of the specific construction ofthe improved strap structures, may be had by referring to the drawingaccompanying and forming a part of this specification wherein likereferences characters designate the same or similar parts in the variousviews.

Fig. 1 is a fragmentary plan view of one of the blanks utilized in myimproved mode of strap production, showing the sheet-metal blank punchedpreparatory to distortion thereof into semi-circular strap formation;

Fig. 2 is an enlarged central section through one end of a strapassembly, showing one of the boss forming tubes in place preparatory tofinal attachment thereof to the strap end;

Fig. 3 is a sectional view similar to that of Fig. 2, showing the bossforming tube finally clamped between the integral flanges at the end ofthe strap;

Fig. 4 isa top viewof a completed strap assembly; Q

Fig, 5 is a side elevation of a completed strap assembly showing one endthereof in section; and Fig. 6 isan end view of one of the completedstrap structures. 3

While the invention has been shown and described herein as beingespecially applicable to the production of semi-circular sheet-metalstrap structures formed of metal such as aluminum, and especiallyapplicable to the airplane industry, it is not my desire or intent tothereby unnecessarily restrict the scope or utility of the improvementwhich may obviously be more gen erally applied to the production ofstraps for other purposes.

1 Referring to the drawing, the improved sheetmetal strap structureshown in Figs. 4, 5 and 6, is preferably formed of light metal havinghigh tensile strength, such as aluminum, and comprises in general asemi-circular band 8 having integral laterally spaced outwardly directedflanges 9, I0 at its opposite ends and also being provided with anintegral side flange ll and a spacing tube l2 interposed between eachset of the end flanges 9, I0. Th'e flanges 9, ID are provided withalined circular holes l3, I4 respectively, with which the centralopening l5 of the adjacent tubes l2 are also accurately alined, and theopposite ends of each tube 1 2 are snugly confined within recesses I6,ll formed in the respective flanges 9, l0.

Each of the strap bands 8 together with its flanges 9, H), H ispreferably formed of a single fiat sheet of metal by substantially thefollowing method. The blanks are formed with the aid of punches anddies, as shown in detail in Fig. 1, with the band 8 and flanges 9, III,II disposed in a common plane and having the circular holes I3, 14punched through their respective end flanges 9, l; and in order toprevent tearing of the metal a small hole l8 may be pierced at each ofthe opposite sides of each flange 9. The successive blanks maythereafter be distorted to properly curve each band B, to dispose theside flange H approximately perpendicular to the band portion, and toposition the plane end flanges 9, l0 outwardly and spaced apart so as tosnugly receive the bushings or tubes 22 therebetween as illustrated inFig. 2. When the blanks have been thus distorted and the spacing tubesI2 have been temporarily assembled between the sets of end flanges 9,In, the flange and tube assemblies may be subjected to a punch which isadapted to press the opposite ends of each tube I2 into the adjacentflanges 9, l0 so as to further distort these flanges and to formthe'r'etaining recesses l6, ll, thereby snugly confining each bushing ortube 12 between the corresponding strap flanges 9, Ill with its centralopening IS in accurate alinement with the flange holes 13, I4, andcompleting the successive bosses.

The successive strap structures when thus completed may be used fordiverse purposes, by applying clamping bolts or studs and nuts, to theboss assemblies at the opposite ends thereof' When such clampingelements are applied to the boss structures of the improved straps, theflanges 9, it are obviously firmly clamped against the opposite ends ofthe intervening spacing sleeves or tubes l 2, and the bosses aresubjected to compression so that the tubes will remain confined withintheir retaining recesses I6, I 1. The band 8 which is re-enforced by theside flange I I, may be placed under considerable tension withouttearing or rupturing by virtue of the provision of the holes l8 at theinner ends of the flanges 9 which have been struck out of the body ofthe blank, and also due to the fact that the flanges 9, ill are formedintegral with the band ends and no heating operation such as welding orsoldering, is utilized in. producing the strap assemblages.

From the foregoing detailed description it will be apparent that mypresent invention provides an improved mode of producing attachingstraps having clam-ping bosses at the opposite ends thereof, fromrelatively thin sheet material, with the aid of punches and dies andwithout utilizing heat. The successive strap structures can be quicklyand accurately produced so that absolute accuracy and uniformity result,and although the straps appear quite frail and light, they are adaptedto effectively resist considerable pressure without breaking or becomingundesirably distorted. The improved attaching straps may also beconstructed with the aid of relatively simple machinery and the endbosses thereof are extremely strong and are properly positioned forreception of the attaching elements. The invention has proven highlysuccessful in actualcommer'cial use, especially as applied to themanufacture of airplane parts, and it has been found that the strapsmanufactured in accordance with this improvement may also be produced atminimum cost and at maximum speed.

It should be understood that it is not desired to limit this inventionto the exact details of construction or to the precise steps of themethod, herein shown and described, for various modifications within thescope of the claims may occur to persons skilled in the art.

I claim:

1. An article of manufacture, comprising, a sheet-metal stra havingintegral outwardly directed approximately parallel sets of flanges atits opposite ends, the flanges of each set having alined holes therein,and a tubular spacer snugly confined between each set of said endflanges concentric with said alined holes.

2. An article of manufacture, comprising, a longitudinally curvedsheet-metal strap having integral outwardly directed approximatelyparallel sets of flanges at its opposite ends, each flange beingprovided with a central hole and an annular recess formed concentricwith the hole and recess of the other flange of the same set, and atubular spacing sleeve snugly confined in the flange recesses of eachset centrally of the adjacent holes.

3. An article of manufacture, comprising, a sheet-metal longitudinallycurved strap having integral outwardly directed approximately parallelsets of flanges at its opposite ends, the flanges of each set havingalined holes therein, a tubular spacer snugly confined between each setof said end flanges in alinement with said alined holes, and a planeside flange formed integral with the strap and extending inwardly fromend to end thereof.

4. An article of manufacture, comprising, a longitudinally curvedsheet-metal strap having integral outwardly directed approximatelyparallel sets of flanges at its opposite ends, each flange beingprovided with a central hole and an annular recess formed concentricwith the hole and recess of the other flange of the same set, a tubularspacing sleeve snugly confined in the flange recesses of each setcentrally of the adjacent holes, and a longitudinally curved side flangeformed integral with the strap and extending from one set of flanges tothe other.

5'. An article of manufacture, comprising, a longitudinally curvedsheet-metal strap having integral outwardly directed approximatelyparallel flanges near an end thereof each having a hole therein coaxialwith the hole in the other flange, and a tubular spacer confined betweensaid flanges in axial alinement with said holes and being disposedtangential to the curved strap.

6. An article of manufacture, comprising, a longitudinally curvedsheet-metal strap having integral outwardly directed'approximatelyparallel flanges near an end thereof each having a hole therein coaxialwith the hole in the other flange, eaclrof said flanges also having anannular recess adjoining the hole therein and facing the other flange,and a tubular spacer having its opposite ends confined within saidflange recesses and being disposed in axial alinement with said holesand tangential to said end of the curved strap.

HERBERT LESLIE ZIMMERMAN.

